The present invention relates to the field of turbine engines, and in particular to a device for temporarily increasing power of at least a first turbine engine.
In the present context, the term “turbine engine” is used to mean any machine enabling thermal energy from a working fluid to be converted into mechanical energy by said working fluid expanding in a turbine. More particularly, the working fluid may be a combustion gas resulting from chemical reaction between a fuel and air in a combustion chamber. Thus, turbine engines, as understood in the present context, include among other things, straight-flow or bypass turbojets, turboprops, turboshaft engines, and gas turbines. In the description below, the terms “upstream” and “downstream” are defined relative to the normal flow direction of the working fluid through the turbine engine.
In certain circumstances, it can be desirable to increase temporarily the power of a turbine engine. For example, in a power plant comprising a plurality of turbine engines, the failure of one of them may make it necessary, temporarily during an emergency period, to increase the power of the others in order to compensate for the loss of power from the turbine engine that has failed.
One of the solutions known to the person skilled in the art for obtaining such a temporary increase in power is to inject a coolant liquid, which may be constituted, by way of example, by water or a mixture of water and an antifreeze, e.g. methanol, ethanol, or glycol, this liquid being injected into the air admission upstream from the combustion chamber. This injection serves firstly to cool the air upstream from the combustion chamber, thereby increasing its density and thus the mass flow rate of oxygen admitted into the combustion chamber. Secondly, the vaporization of this coolant liquid in the combustion chamber serves to increase very significantly the pressure and/or the volume flow rate downstream from the combustion chamber, and thus serves to increase very significantly the mechanical work recovered in the turbine.
Nevertheless, on-board vehicles, and in particular aircraft, the use of such a coolant liquid is limited by the weight of the coolant liquid that can be carried by the vehicle. In British patent application GB 2 046 681 A, proposals are made to feed the aircraft with coolant liquid from a stationary tank.
Nevertheless, that solution is clearly practical only if the aircraft is also stationary or almost stationary.
The desire to have additional power available for a period that is as long as possible, is thus in direct conflict with the desire to minimize the additional weight constituted by the coolant liquid.
Furthermore, when the purpose of this temporary increase in power is to compensate for the failure of another turbine engine, it is also desirable for this increase to be triggered automatically and as quickly as possible.